Hey Ron,
Found a source for your shielded servo leads. Buy this and solder your connectors on and solder the fourth wire to the negative wire at on end only for shielding. A bit pricy at .75 per foot at B & B Specialties. If you have a source for computer wire this four terminal wire is black, white, red and a bare ground (this is your sheild wire) and can be had for as little as .10 to .20 cents per foot if you could find it this way. If not, and you don't mind spending $6 or $8, here it is:

http://www.bennettbuilt.com/page8.htm